Is it true my body is not entirely alive?

The dead bits that keep us kicking

So you think you’re all alive? Think again. As strange as it may seem, the human body is not entirely "alive". A small part of us is not alive, never has been, and never will be. Ironically, what's not alive is vital to what is.

Ninety-six per cent of the human body is alive. This part is composed of living, "organic elements" present in many different forms. DNA, RNA proteins, lipids, and sugars are all composed of primarily oxygen, carbon, hydrogen, and nitrogen. In addition, water (H2O) and carbon dioxide (CO2) as well as other small molecules are involved in these elements. The proportions are oxygen (65 per cent), carbon (18.5 per cent), hydrogen (9.5 per cent), and nitrogen (3.2 per cent).

The remaining 3.8 per cent of the human body is technically composed of non-living, "non-organic elements" in the form of salts. Although their quantities are fairly miniscule, they are absolutely critical for the maintenance of the body's structure and smooth working order. For example, calcium is a major component of bones and teeth. Potassium keeps the heart beating evenly and regularly. Iron is necessary for the movement of oxygen by red blood cells.

The breakdown of this 3.8 per cent consists of calcium (1.5 per cent), phosphorus (1.0 per cent), potassium (0.4 per cent), sulphur (0.3 percent), chlorine (0.2 per cent), sodium (0.2 per cent), iodine (0.1 per cent), iron (0.1 per cent), and magnesium (0.1 per cent). The remaining 0.5 per cent is composed of trace elements, including chromium, cobalt, copper, fluorine, manganese, molybdenum, selenium, tin, vanadium, and zinc.

Some of these trace elements are part of critical body enzymes. Without these enzymes we’d die and all of our body wouldn't be alive.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

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